The present invention relates to a chemiluminescent device which, for a given lighted surface area, requires less chemicals without substantially decreasing the light output.
Chemiluminescent devices are well known. They operate in a known manner through the mixture of a first and a second known chemical. When these two chemicals mix, the resulting liquid emits light, i.e. luminesces.
FIG. 1a is a sectioned view of the construction of a prior art chemiluminescent device in the form of what is known as a light stick 100. The light stick 100 illustrated in FIG. 1a is shown in a sectioned view. In FIG. 1a, a longitudinal axis is defined along the elongated dimension of the light stick, i.e. a horizontally in FIG. 1a. A transverse dimension is defined perpendicular to the longitudinal axis, i.e. into and out of the figure. The light stick 100 has a circular transverse cross-section. One skilled in the art will understand, however, that any transverse cross-sectional shape may be used. The light stick 100 consists of an outer container 10 which is closed at the right hand side 12 of FIG. 1a. Also at the right hand side 12 of the light stick 100 is a mounting flange 14. The front view of the mounting flange 14 is shown in FIG. 1c, and includes a mounting hole and stiffeners. The outer container 10 is open at the left hand side of FIG. 1a. A cap 16 is attached to the open end of the outer container 10 sealing the outer container. The interior surface of the outer container 10, when it is sealed by the cap 16, defines an interior space 11. An inner container 18 is placed within the interior space 11.
The inner container 18 is formed of a relatively brittle material, preferably glass. The outer container 10 is transparent or translucent, to maximize light transmission; and is fabricated from a material which is relatively flexible. The outer container is preferably LDPE plastic having a thickness of around 0.065 inches which may be formed using injection molding. The cap 16 is fabricated of a material which may be easily attached to the outer container 10. The cap may also be formed using injection molding and in the preferred embodiment is also LDPE plastic.
The inner container 18 is initially an open glass tube with one closed end. It is filled with the first chemical, then the other end is sealed by heating the open end of the tube, melting the glass until that end is sealed. The filled and sealed inner container 18 is placed inside the outer container 10. The outer container 10 is then filled with the second chemical and the cap 16 attached to the open end, all in a known manner.
The cap 16 may be sealed to the outer container 10 by any of a variety of known means, such as heat staking or sonic welding. In a preferred embodiment, the cap 16 is friction welded to the open end of the outer container 10 by being spun rapidly on the outer container until friction raises the temperature of the plastic at the mating surfaces of the outer container 10 and the cap 16 to, or just past, the melting point. Plastic from the cap and outer container fuse forming a sealed joint. The joint is then cooled and a welded seal is formed, all in a known manner. In FIG. 1a, the cap 16 is formed with a recess for the outer container 10 so that there are mating surfaces between the cap and both the outside and the inside surfaces of the outer container 10. This arrangement stabilizes the cap 16 on the opening, and enables the cap to remain centered while being sealed to the outer container 10.
FIG. 1b shows an alternative cap 16xe2x80x2. The cap 16xe2x80x2 has a simple shape and has a mating surface only for the outside surface of the outer container 10. The cap 16xe2x80x2 may be fabricated of the same material as cap 16 (FIG. 1a) and attached to the outer container 10 in the same manner. Cap 16xe2x80x2 has about one-half the sealing area, and, thus, may be more prone to faulty sealing and consequent leakage and failure than the cap 16 illustrated in FIG. 1a. 
In operation, the user flexes the light stick 100, breaking the inner container 18. The first chemical in the inner container 18 mixes with the second chemical in the interior space within the outer container 10, and the resulting liquid begins to luminesce.
One problem with such luminescent devices is that the chemicals are relatively expensive. Thus, a light stick of a given lighted surface area which can produce substantially the same intensity of light, but use less chemicals is desirable. Another problem occurs in the application of such light sticks in commercial fishing. In this environment, the light sticks are subject to great external pressure from water depths of a mile or more. Light sticks used in this environment sometimes fail. It is believed that it is the presence of air within the outer container which causes this failure. While the liquid in the light stick is incompressible, the air is compressible. If enough air is trapped within the light stick, it will compress and the light stick will deform, sometimes to the point of rupturing it. Thus, a light stick in which the amount of air trapped can be minimized is believed to be desirable.
The inventor realized that light is emitted only from the outer surface of the outer container 10. The luminescing liquid in the transverse middle of the outer container contributes relatively little to the light output of the light stick 100, compared to the liquid close to the outer surface. In accordance with principles of the present invention, a chemiluminescent device, includes an outer container, having an interior surface defining an interior space, and an insert, placed in the interior space, and separated from the interior surface of the outer container 10.
The insert takes up some of the interior space, which, thus, requires less chemical to fill. However, the insert is separated from the interior surface of the outer container 10. For example, it is placed in the transverse middle of the interior space. Consequently, luminescing chemical is displaced only from the middle of the interior space, which liquid would have contributed relatively little to the light intensity output from the light stick, as described above. The luminescing chemical is still in contact with the same surface area of the outer container 10, and the light intensity, thus, is not significantly decreased. Furthermore, for the same reason that less chemical is required to fill the light stick, less air will tend to be trapped in the light stick decreasing the chance of deformation and failure in a high pressure environment.